#include<stdio.h>
int main(void)
{
    float k = 0.5454f;
    float b = 4.090f;
    float x, y;
    printf("Input a number x:\n");
    scanf("%f", &x);
    if((x >= 0) && (x < 9))
    {
        y = x;
        printf("The result of the function is %.3f", y);
    }
    else if ((x >= 9) && (x <= 20))
    {
        y = k * x + b;
        printf("The result of the function is %.3f", y);
    }
    
    else
    {
        printf("The number is out of side!\n");
    }
    //printf("The result of the function is %.3f", y);
    return 0;
}